(a) Field of the Invention
The present invention relates to a plasma display panel (PDP), and more particularly, to discharge sustain electrodes of a PDP.
(b) Description of the Related Art
A PDP is a display device that uses vacuum ultraviolet rays generated by gas discharge in discharge cells to excite phosphors, thereby realizing the display of images. With its ability to realize high-resolution images, the PDP is emerging as one of the most popular flat panel display configurations used for wall-mounted televisions and other similar large-screen applications. The different types of PDPs include the AC PDP, DC PDP, and the hybrid PDP. The AC PDP utilizing a triode surface discharge structure is becoming the most common configuration.
In the AC PDP with a triode surface discharge structure, an address electrode, barrier ribs, and a phosphor layer are formed on a rear substrate corresponding to each discharge cell. Discharge sustain electrodes including scanning electrodes and display electrodes are formed on a front substrate. A dielectric layer is formed covering the address electrodes on the rear substrate, and, similarly, a dielectric layer is formed covering the discharge sustain electrodes on the front substrate. Also, discharge gas (typically an Ne—Xe compound gas) is filled in the discharge cells.
Using the above structure, an address voltage Va is applied between the address electrodes and the scanning electrodes such that address discharge occurs in the discharge cells. As a result of this address discharge, a charge is accumulated on the dielectric layer that is formed covering the discharge sustain electrodes. This charge is referred to as a wall charge. A space voltage formed between the scanning electrodes and the display electrodes as a result of the wall charge is referred to as a wall voltage Vw. The discharge cell in which illumination is to occur is selected by the wall charge.
Next, a discharge sustain voltage Vs is applied between the display electrode and the scanning electrode of the selected discharge cell. Plasma discharge is effected when the sum of the discharge sustain voltage Vs and the wall voltage Vw exceeds a discharge firing voltage Vf. Accordingly, vacuum ultraviolet rays are emitted from Xe atoms that are excited by plasma discharge. The vacuum ultraviolet rays excite phosphors so that they glow (i.e., emit visible light) and thereby enable color display.
In the PDP operating in this manner, the formation of the discharge sustain electrodes greatly affects sustain discharge characteristics. Transparent material such as indium tin oxide (ITO) is typically used for the conventional discharge sustain electrodes. That is, the conventional discharge sustain electrodes are typically transparent electrodes. This transparency allows visible light generated in the discharge cells to pass through the discharge sustain electrodes while the discharge sustain electrodes perform their function of effecting sustain discharge. A thickness of the transparent discharge sustain electrodes is approximately 1000-1300 Å.
However, the transparent electrodes used for the discharge sustain electrodes are expensive. Manufacturing costs are further increased by the fact that it is necessary to perform an additional patterning process of the transparent electrodes. In addition, because of the high resistance of the transparent electrodes, bus electrodes made of a metal with a low resistance are further needed.
As a result of these problems, many in the field are attempting to realize the discharge sustain electrodes using only metal electrodes instead of the transparent electrode/metal electrode combination. An example of such usage is disclosed in U.S. Pat. No. 6,522,072. In this patent, discharge sustain electrodes are formed using only metal electrodes that are cheaper to manufacture than transparent electrodes. However, discharge sustain electrodes made using metal electrodes such as in the referenced patent reduce an aperture ratio of the PDP such that illumination efficiency is decreased and screen brightness is reduced. If the space between adjacent metal electrodes positioned in discharge gaps is increased in an effort to enhance the aperture ratio, the discharge firing voltage is increased and sustain discharge becomes unstable. An improvement in this regard, therefore, is needed.